Self-aligning electrical contact shoes for movable carriers



H. G. ABBEY Feb. 23, 1965 SELF-ALIGNING ELECTRICAL CONTACT SHOES FOR MOVABLE CARRIERS Filed Feb. 25, 1963 INVENTOR.

United States Patent 3,171,005; SELF-ALIGNING ELECTRICAL CONTACT SHOES FOR MOVABLE CARRIERS Harold Abbey, 189-10 Aberdeen Road, Jamaica 23, Long Island, NY. Filed Feb. 25, 1963', See. No. 260,388 5 Claims. (Cl. 200.-166) This invention pertains generally to electrical contacts, and more particularly to a self-aligning contact shoe which is driven into engagement with a fixed contact element and effects a positive connection therewith despite any initial misalignment in the relative positions of the two contacts.

In many conveyor systems, such as those used for electroplating, loads are borne by carriers on a trackway,

the individual carriers being electrified when arriving.

at a work station. Inmy prior Patent 2,979,181, issued April 11, 1961, there is disclosed afree-wheeled carrier system wherein power is applied to a carrier when it enters a work station, where electrification is required, this being accomplished by a spring-type contact shoe supported on the carrier. Upon entering a. station along a horizontal trackway, the shoe on the carrier engages a fixed bus bar to make positive contact. therewith, which allows for live entry of the load into an electroplating solution; Such shoes also permit unbrokencontact when vertical movement of the carrier is required.

In contact shoes of the construction disclosed in my prior patent and of the type used in various other forms of electrification systems, the contact element is supported on helical springs which are compressed when the element moves into engagement with a fixed contact, the springs urging the shoe into positive contact. One disadvantage of such arrangement is that the springs are electrically conductive, and it becomes necessary therefore to mount the springs on insulators if the contact shoe is to be electrically isolated from its supporting carrier.

Another drawback, which is of greater importance, is that resilience or compressibility of the spring is greatest in the axial direction, the action of the spring being nonlinear if stressed in any other direction. Hence where the shoe is misaligned with the fixed contact, the spring rather than acting to correct such misalignment, may instead tend to worsen this condition.

Where, for example, the spring-mounted shoe is borne on a carrier moving along a trackway, the position of the carrier may veer somewhat from its normal position on the trackway by reason of play in the trolley wheels, unbalanced loads, or other factors causing the carrier to deviate from its assigned position. This causes the shoe to shift from its usual location and the shoe, on entering a station, may be laterally or angularly displaced relative to the fixed bus bar rather than directly in line therewith. When this occurs and the shoe then engages the bus bar, the springs are acted upon nonaxially and their deflection may serve to further displace the shoe with a resultant poor contact.

Accordingly, it is the principal object of this invention to provide a resiliently-mounted contact shoe which readily yields when subjected to pressure in any direction to effect positive contact with a fixed contact element.

More specifically, it is an object of the invention to provide a carrier-borne contact shoe in which the resilient elements are formed of a cellular, electrically-insulating material which is equally compressible in all directions and causes the contact element supported thereon to align itself with the fixed contact.

A significant advantage of the invention is that the resilient elements serve to support the contact shoe on 3,171,005 Patented Feb. 23, 1965 ICC a mounting plate and at the same time to isolate the shoe from the plate, thereby obviating the need for insulating members. Thus the shoe assembly is of simple and effi'cient design, and is. reliable in operation for prolonged periods. Another advantage of the invention is that it makes possible a contact shoe assembly which may be. manufactured at low cost.

Briefly stated, these objects are accomplished in a contact assembly comprising, a. contact shoe which is supported by cellular plastic columns on a mounting plate, the columns acting as resilient insulating pads equally compressible in any direction and affording a constant contact pressure on the shoe.

For a better understanding of the invention, as well as further objects and features thereof, reference is made. to the following detailed description to be read in conjunction with the accompanying drawings, wherein:

FIG. 1' is a perspective view of a preferred embodiment of a contact-shoe assembly in accordance with the invention;

FIG. 2, shows three such contact shoe assemblies borne. on a single carrier; and

FIG. 3 illustrates in rear plan view, the contact shoe element.

Referring now to the drawing, and more particularly to FIG. 1, a contact shoe assembly in accordance withv the invention comprises a contact shoe 10 resiliently supported by a pair of spaced columns or posts 11 and 12 on a mounting plate 13'. Connection to the shoe is made by means of a flexible strap 14.

The shoe, which is formed of a highly conductive metal plate resistant to arcing, such as bronze or silver, is generally rectangular in form, the ends 10a and 10b of the shoe being chamfered to facilitate entry when engaging a fixed contact element in either direction of shoe movement. The mounting plate 13 is preferably a steel plate, While the resilient posts are formed of a compressible insulating material having a rectangular crosssection. The strap 14 may be made of woven copper or brass, and is brazed or soldered to the under-surface of the shoe. A flexible cable is soldered to the strap for connection to a power source.

The posts are preferably formed of a cellular resilient plastic material such as neoprene, polyurethane foam, or other material in which the cells are sealed. This is important, for if the cellular material is sponge-like with interconnecting pores, it tends to absorb moisture, with a resultant reduction in its insulating characteristics. The ends of the posts are directly bonded to the mounting plate and to the shoe by means of suitable metal-toplastic cement or adhesives, such as epoxy resins.

The posts are equally compressible in all directions, whereby the shoe is caused to align itself with the fixed contact regardless of any initial misalignment in the shoe position. Thus in FIG. 1, if we regard the X axis as the longitudinal axis, and the Y axis as the transverse axis of the shoe, it will be seen that the shoe is capable of a small displacement about either axis and in effect to undergo roll, yaw and pitch deviations. Ideally, the shoe lies in a plane parallel to the fixed contact element which it is to engage. But in the event the shoe is displaced from this ideal plane, as long as it is able to ride under the fixed plate, it will be caused by the posts to assume the ideal plane against the contact element.

The two posts may in practice undergo different degrees of compression, where, for example, the shoe is tipped somewhat relative to the fixed bus bar when entering a station. When, however, the posts are compressed, they apply an upward pressure in directions causing the shoe to align itself with the fixed bus or other engaged contact.

In FIG. 2, three contact shoe assemblies A, B and C are mounted on the arms 15 of a carrier (not shown) which rides along a horizontal trackway. Shoes A and B are mounted on either side of an arm on a bracket 16 attached to the lower wall of the arm, these shoes being intended to engage fixed vertical contact saddles when the carrier is caused by an elevator to move in the vertical direction relative to the trackway.

The shoe assembly C is mounted directly above the arm to engage a horizontal bus bar 17 when, for example, the carrier enters a station. The resilient posts act to isolate the shoes electrically from the carrier arm, connections to the shoes being made by soldering cables to the straps 14.

Thus it will be seen that the construction of the shoe assemblies is uncomplicated and yet the shoes act more effectively than the more complex and costly conventional spring-loaded structures.

While there has been shown a preferred embodiment of contact shoes in accordance with the invention, it will be appreciated that many changes and modifications may be made therein without, however, departing from the essential spirit of the invention as defined in the annexed claims.

What is claimed is:

1. An electrical contact shoe assembly adapted to be borne by a moving carrier to engage a planar fixed contact, said carrier moving along a trackway parallel to said fixed contact but being subject to minor misalignment, said assembly comprising a mounting plate for attaching said assembly to said carrier, a compressible body secured to said plate, and a fiat contact shoe bonded to said body, whereby said body is compressive when said shoe slidably engages said fixed contact to urge said shoe thereagainst, said body being equally compressible in all directions to cause said shoe to align itself with said fixed contact regardless of how said carrier is misaligned, said compressible body being formed of cellular insulating material whose cells are closed.

2. A self-aligning electrical contact shoe assembly adapted to be borne by a moving carrier to engage a planar fixed contact, said carrier moving along a trackway parallel to said fixed contact but being subject to minor misalignment, said assembly comprising a metallic mounting plate for attaching said assembly to said carrier, 21 pair of posts afiixed at spaced positions to said plate, and a flat contact shoe bonded to the ends of said posts, said posts being formed of a cellular insulating material whose cells are closed and which is compressible in all directions to cause said shoe to align itself with said fixed contact when said shoe makes sliding engagement therewith and regardless of how said carrier is misaligned.

3. An assembly as set forth in claim 2, wherein said posts are formed of neoprene.

4. An assembly as set forth in claim 2, wherein said posts are formed of foamed polyurethane.

5. An assembly as set forth in claim 2, further including a woven metallic connecting strap soldered to the under-surface of said shoe between said posts.

References Cited in the file of this patent UNITED STATES PATENTS 2,435,114 Adam et al. Jan. 27, 1948 2,528,086 Schenck Oct. 31, 1950 2,579,523 Terry Dec. 25, 1951 3,021,307 Csendes Feb. 13, 1962 3,054,759 Britain Sept. 18, 1962 

1. AN ELECTRICAL CONTACT SHOE ASSEMBLY ADAPTED TO BE BORNE BY A MOVING CARRIER TO ENGAGE A PLANAR FIXED CONTACT, SAID CARRIER MOVING ALONG A TRACKWAY PARALLEL TO SAID FIXED CONTACT BUT BEING SUBJECT TO MINOR MISALIGNMENT, SAID ASSEMBLY COMPRISING A MOUNTING PLATE FOR ATTACHING SAID ASSEMBLY TO SAID CARRIER, A COMPRESSIBLE BODY SECURED TO SAID PLATE, AND A FLAT CONTACT SHOE BONDED TO SAID BODY, WHEREBY SAID BODY IS COMPRESSIVE WHEN SAID SHOE SLIDABLY ENGAGES SAID FIXED CONTACT TO URGE SAID SHOE THEREAGAINST, SAID BODY BEING EQUALLY COMPRESSIBLE IN ALL DIRECTIONS TO CAUSE SAID SHOE TO ALIGN ITSELF WITH SAID FIXED CONTACT REGARDLESS OF HOW SAID CARRIER IS MISALIGNED, SAID COMPRESSIBLE BODY BEING FORMED OF CELLULAR INSULATING MATERIAL WHOSE CELLS ARE CLOSED. 